Metal casting is often performed using sand moulds which are produced in machines that produce sand moulds or sand mould parts which are placed in a string one after the other, and transported to a pouring station where the space between these moulds or mould parts is filled with metal. These machines often include core setters to insert cores between the moulds or mould parts.
These mould producing machines typically comprise a generally rectangular moulding chamber in which the sand is introduced (for example, by blowing or by gravity), through a hopper or bell arranged above the moulding chamber. Said chamber is closed by means of two closing elements or plates, such as a front plate and a rear plate, between which the sand is pressed to configure the mould or mould part. For example, one of said plates can be a mobile and swivelling front plate arranged allow the exit of the mould or mould part, and the rear plate can be arranged at the opposite end of the chamber and be associated with a compaction piston, which also serves to perform the pushing and corresponding expulsion of the mould through the front end of the chamber. In this kind of machine, the obtaining of the mould can start with the introduction of the sand in the moulding chamber. Next, in a compression phase of the moulding cycle, the sand is pressed between the front and rear plate. Then, in what can be called the extraction phase of the moulding cycle, the front plate is opened and tilted to allow the exit of the mould, which is achieved by means of the push of the rear plate, thus causing the extraction of the mould from the moulding chamber. Machines of this type are described in, for example, U.S. Pat. Nos. 7,007,738 and 6,092,585. These patents describe vertical mould moulding machines comprising a moulding chamber which is closed by means of a shiftable and swiveling front plate and a rear plate provided at an end of an extraction piston, the sand mould being compacted by the opposing pressure of the two plates. In this way, moulds are obtained cyclically, and expelled from the moulding chamber, aligned and placed against one another forming a string which can be transferred towards the pouring station, etc. Other examples of vertical mould forming machines are described in U.S. Pat. No. 4,442,882, EP-A-1101548, WO-A-01/12360, EP-A-1219830, U.S. Pat. No. 7,806,161 and EP-A-2357050.
Generally, the front and the rear plates are provided with pattern plates, as explained in, for example, U.S. Pat. No. 7,806,161, said pattern plates being selected in accordance with the pattern or shape to be given to the front and rear surfaces of the mould. Thus, when the machine is to be used to produce moulds differing from the previously produced moulds, the pattern plates have to be changed. The pattern plates can be attached to the front and rear plates, also known as squeeze heads or squeeze head plates, using any suitable means. The change of pattern plates generally involves removing the previously used pattern plates from the front and rear plates, respectively, and connecting the new pattern plates to the front and rear plates, respectively. This operation has conventionally been performed manually. As the pattern plates can be rather heavy, sometimes the operator has used some kind of lifting device.